The present invention relates primarily to clinical diagnostic apparatus and more particularly to apparatus for conducting diagnosis by electrophoresis.
Electrophoresis is a valuable diagnostic aid in a clinical laboratory which is limited in potential use because it requires many time consuming steps. Automation could greatly extend its application and permit wider use in routine patient screening. In electrophoresis, an electrophoretic medium, such as a gel or microporous membrane, has implanted into the surface thereof a sample material and (optionally) a reference material. A direct current electrical field is then applied across the medium. The various constituents (most often proteins) contained in the reference material (if used) and sample material will be caused to move in varying amounts across the medium as a result of this electrical field. After enough time has elapsed to cause migration over a sufficient distance to provide separation between the constituents capable of analysis, the electrical field is removed and a stain is applied to the medium which affects only the electrophoretically separated constituents therein. The medium itself is then caused to become transparent whereby the separated bands of stained, migrated reference and sample components will appear on a transparent background and can be analyzed by appropriate apparatus. By comparison of the sample bands to that of the reference bands, the composition of the sample material can be determined.
The actual electrophoresis process wherein the electrical field is applied is rather time consuming. Traditionally, this has been accomplished by affixing one or more pieces of support material containing the electrophoretic medium into a fixed chamber for the required time duration. The chamber is then opened and the batch removed and further processed. Once the processing of one or more samples within the chamber is started, the process must be completed before processing additional samples.
Patents typical of the prior art include that to Dwyer et al. (U.S. Pat. No. 3,594,263) disclosing a laminated sheet for electrophoresis comprising a flexible but stiff base sheet to which a separate microporous plastic membrane sheet is bonded. The laminated sheet is then used in a batch process electrophoresis chamber as shown in FIG. 1 of the Dwyer et al. patent.
In the patent to Saravis (U.S. Pat. No. 3,764,513), apparatus is shown employing a continuous backing member having a gel layer on its upper surface. A novel wicking arrangement is employed in a lid for the electrophoretic chamber whereunder a portion of the continuous backing member is disposed. With the lid lowered in position, the electrical field is established in the gel layer under the cover and a batch electrophoresis operation is conducted on that limited segment of the backing member. When the electrophoresis is complete, the used backing is moved out for analysis and a fresh portion assumes the active position under the lid. While employing a continuous backing member, the apparatus of Saravis still only discloses means for conducting batch process electrophoresis.
The patent to Hrdina (U.S. Pat. No. 3,303,120) teaches an improved batch process apparatus for paper electrophoresis wherein electrical contact is established by dipping the ends of the paper electrophoretic medium into electrolyte troughs during the electrophoresis process. To improve the waiting time until the next batch can be inserted, the apparatus of Hrdina employs means for moving the electrolyte trough away from contact with the ends of the paper and substituting a drip trough therefor. Drying air is then applied to dry the paper before its removal.
Therefore, it is an object of the present invention to provide apparatus for accomplishing the electrophoresis step per se on a continuing basis wherein the processing of additional samples can be started at any time while the processing of previously started samples can continue through to completion.